ci(qemu): Support read timeout in qemu tests

This is required for GET_SECURITY_INFO usage and any other case where
commands not being accepted will result in a timeout.

test/serial_io_tcp.cpp

@@ -1,4 +1,4 @@
-/* Copyright 2018-2023 Espressif Systems (Shanghai) CO LTD
+/* Copyright 2018-2024 Espressif Systems (Shanghai) CO LTD
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,6 +32,7 @@ using namespace std;
 const uint32_t PORT = 5555;
 static int sock = 0;
 ofstream file;
+static chrono::time_point<chrono::steady_clock> s_time_end;
 
 #if SERIAL_FLASHER_DEBUG_TRACE
 static void transfer_debug_print(const uint8_t *data, uint16_t size, bool write)
@@ -115,26 +116,36 @@ esp_loader_error_t loader_port_write(const uint8_t *data, uint16_t size, uint32_
 
 esp_loader_error_t loader_port_read(uint8_t *data, uint16_t size, uint32_t timeout)
 {
-    uint32_t written = 0;
-    int bytes_read = 0;
+    // Timeout is specified in milliseconds, split to seconds and microsecond remainder
+    const struct timeval timeout_values = {
+        .tv_sec = timeout / 1000,
+        .tv_usec = (timeout % 1000) * 1000
+    };
+
+    if (setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
+                   (const char *)&timeout_values, sizeof(timeout_values)) != 0) {
+        cout << "Could not set socket read timeout\n";
+        return ESP_LOADER_ERROR_FAIL;
+    }
 
-    do {
-        bytes_read = read(sock, &data[written], size - written);
-        if (bytes_read == 0) {
+    const int bytes_read = read(sock, data, size);
+
+    if (bytes_read != size) {
+        if (errno == EWOULDBLOCK || errno == EAGAIN) {
+            cout << "A socket read timeout occurred\n";
+            return ESP_LOADER_ERROR_TIMEOUT;
+        } else {
             cout << "Socket connection lost\n";
             return ESP_LOADER_ERROR_FAIL;
         }
+    }
 
 #if SERIAL_FLASHER_DEBUG_TRACE
-        transfer_debug_print(data, bytes_read, false);
+    transfer_debug_print(data, bytes_read, false);
 #endif
 
-        file.write((const char *)&data[written], bytes_read);
-        file.flush();
-
-        written += bytes_read;
-    } while (written != size);
-
+    file.write((const char *)data, size);
+    file.flush();
 
     return ESP_LOADER_SUCCESS;
 }
@@ -157,11 +168,15 @@ void loader_port_delay_ms(uint32_t ms)
 
 void loader_port_start_timer(uint32_t ms)
 {
-    (void)ms;
+    s_time_end = chrono::steady_clock::now() + chrono::milliseconds(ms);
 }
 
 
 uint32_t loader_port_remaining_time(void)
 {
-    return 1;
+    const auto remaining = s_time_end - chrono::steady_clock::now();
+
+    const auto remaining_ms = chrono::duration_cast<chrono::milliseconds>(remaining).count();
+
+    return (remaining_ms > 0) ? (uint32_t)remaining_ms : 0;
 }